Mucosal transmission represents the predominant mode of global HIV acquisition. Oral transmission is rare. However, it does occur, in adults and in infants, with the latter occurring most likely through ingestion of milk from HIV-infected mothers. If an effective vaccine can be formulated for orally delivery, it is likely to protect not only against oral and other mucosal transmission, but also enhance vaccine access through its ease of administration, thus providing a cost-effective preventive approach against HIV/AIDS. Over the past two decades, our lab has demonstrated the feasibility of parenteral immunization with a poxvirus prime/protein boost strategy, resulting in complete or partial protection against mucosal SIV or SHIV challenge in macaques. In this application, we propose to extend these findings and to leverage recent developments in natural Toll-like receptor (TLR) ligands and oral formulation technologies to explore the possibility of adapting this immunization approach for oral vaccination against HIV/AIDS. The overall hypothesis we propose is that effective oral delivery of poxvirus and protein vaccines in a prime-boost immunization strategy will generate greater oral and mucosal responses than parenteral immunizations, resulting in protection against mucosal challenge. The Specific Aims are: (1) To evaluate the safety and immunogenicity of oral delivery of a replication competent, attenuated poxvirus vaccine;(2) To evaluate the safety and immunogenicity of protein vaccines adjuvanted with a natural TLR ligand and formulated for oral delivery;(3) To compare the immunogenicity of poxvirus prime and protein boost approach in different oral and parenteral delivery regimens;(4) To evaluate the protective efficacy of oral delivered prime/boost vaccines against mucosal challenge in non-human primate models. Results from these studies are likely to help elucidate the protective mechanisms against HIV/AIDS and inform the clinical development of the poxvirus prime/protein boost immunization concept. PUBLIC HEALTH RELEVANCE: Most HIV infections result from mucosal transmission, including transmissions through the oral mucosa. Orally delivered vaccines are easy to administer and are likely to induce immunity at mucosal sites. In this proposal, we will examine oral formulations and delivery of a prime-boost vaccination strategy for its potential to generate protective immunity in macaque models.